As a young boy, Narendra Damodardas Modi helped his dad serve tea in Gujarat's Vadnagar railway station. At the age of 63, and as leader of India's Hindu nationalist Bharatiya Janata Party, he is about to serve the world's largest democracy as prime minister.

Born on September 17, 1950, into a low-caste family running a small business, his interest in politics was sparked at an early age: At eight, Modi associated with the Rashtriya Swayamsevak Sangh, or the RSS, a powerful Hindu nationalist group which rejected secularism and wanted Hinduism enshrined in the Indian constitution. This policy, Hindutva, remains at the core of the BJP.

It was a logical step when Modi joined the BJP in 1985, as the party licked its wounds after winning just two seats in a disastrous showing in 1984 the Lok Sabha elections.

He rose steadily through the ranks, and was inducted into the national executive in 1991 after aiding Murli Manohar Joshi, a party senior, in his ekta yatra (unity journey) to bolster support.

Four years later, and now a stalwart, Modi worked hard behind the scenes to secure the party victory in Gujarat elections.

Despite his association with Joshi, it was LK Advani, the BJP's most revered leader, who became his chief political mentor.

"It was Advani who mentored Modi when he virtually handpicked him into his team of state apparatchiks after recommendations from a few trusted peers in the late 1980s," writes Nilanjan Mukhopadhyay in Modi's biography, Narendra Modi: The man, the Times.

Anti-Muslim riots

Modi was appointed chief minister of Gujarat, an industrial heartland, in October 2001. But within months, the state was in crisis: more than 1,000 people, mostly Muslims, were killed in a series of anti-Muslim riots.

Modi was accused of doing little to prevent the violence, and was questioned by police amid claims of complicity, but was never charged.

Nevertheless the international response was sharp: a prolonged international boycott, with the US denying the Hindu nationalist a visa.

In his most recent interview, Modi said that the judiciary had been "vibrant" in dealing with riot cases. However a study by Stanford Law School has criticised the low conviction rate in those cases.

Atal Bihari Vajpayee, the former prime minister, wanted to sack Modi after the riots, but he held on after the party stood behind him.

Indeed, the religious polarisation that followed the 2002 riots actually boosted his electoral prospects.

And it was with the downfall of his mentor, Advani, that Modi took his next step to power. Their friendship soured in 2005 when Advani described the founder of Pakistan, Mohammad Ali Jinnah, as "secular" and an "ambassador of Hindu-Muslim unity".

The Jinnah comment alienated the RSS and forced Advani to resign as the BJP’s president - events which eventually created the space that Modi required.

Economy first

Modi continued to build his reputation in Gujarat on economic growth, building an efficient business administration and selling the state to the world: in 2009, the Gujarat government hired the US lobbying and public relations firm, APCO Worldwide, to advertise his state as an investment destination.

Since Modi took control, Gujarat has led the nation in GDP growth and accounts for 16 percent of industrial output, despite having five percent of its population. The western state boasts of uninterrupted power supply and the finest road infrastructure in the country.

However, he was criticised for exaggerating the growth, with his policies benefitting the wealthy more than the poor, and favouring a select few corporations.

Nevertheless, his stock within the BJP continued to grow as he projected himself as a man of development, and a staunch advocate of Hindutva ideology.

Modi’s biographer, Mukhopadhyay, describes him as charismatic, an "extremely hard working person, a good administrator but extremely polarising which is in his [Modi's] political genealogy".

His rise to the top of the BJP was confirmed last year when he became the party's nominee for prime minister - despite the protests of several senior party veterans.

And so, it was with the double whammy of Hindu nationalism and promises of economic nirvana, that the BJP leader mounted his assault on the national elections.

His popularity soared in recent years amid the lackluster performance of the ruling Congress party, which looked clueless in addressing the worsening economic situation in the country.

He focused his speeches on jobs, development, poverty and scams. He complained of "illegal migrants" from Bangladesh, who he warned should "pack their bags" once the BJP came to power.

At an election rally in northeastern state of Assam bordering Bangladesh, Modi alleged that officials in the Congress government were involved in poaching rhinos to make way for settlers.

What kind of India such a polarising personality will create remains to be seen.

William Dalrymple, a historian, wrote in the New Statesman magazine: "India is knowingly taking a terrific gamble on its future, in effect choosing to ignore Modi’s record on civil liberties and human rights in return for putting in place a strong and decisive leader who would be brave enough to make the difficult reforms and provide the firm governance and economic prosperity this country is craving."